My Bach 36BO has a horrendously flat 5th partial; this is bad enough that I cannot use first position to play D4 (D above one upper ledger line in bass clef).
I have seen various players (not going to mention names because I do not want to put pressure on anyone) talk of "cutting" or "trimming" the tuning slide. I guess you might be doing something to the inner tubings (the parts that go into the bell and the gooseneck), but exactly what does it mean? While at it, could you please ( ) include some pictures too if possible so that I can follow exactly which part is being modified? Thank you so much in advance!
I'm not sure if cutting the tuning slide will fix the issue of a specific partial being flat. On my 36H it seemed to help, but how certain partials are tuned based on how a horn is constructed is way above my head. The general idea is that the longer the two cylindrical section are in the bell section (these are the two tubes in the tuning slide), the more wild the partials will be. The catch is that you only get the benefit (if there is one) if you keep the tuning slide pushed in 100% and use your main hand slide to tune everything. This is why they have TIS horns.
For the 36H, I believe that cutting 3/8" of useable length per side makes the bell section closer to how the 35H was conceived, and this makes the partials better. But you're talking about a completely different horn.
Usually you cut the tuning slide when you want to bring the overall pitch of the whole horn up. For example, if you are flat on your first position, even with the tuning slide pushed all the way in, you might cut it.
The procedure involves cutting an equal length off each tuning leg (male end) and oversleeve (female end) on both ends of the tuning slide. So 4 equal cuts, total, 2 on the tuning slide and 2 on the bell section it mates to. I would have a tech do it. Cutting off more than 1/2" of useable length per side (1/4" on each cut) is probably ill advised, but who knows?
I've heard of people who have horns with that partial flat so they use fourth instead but I have never experienced that as a problem on any of my horns (and I have many horns).
1. What I do, that may be of help to me (and to you), is I push the tuningslide in all tte way and then play the first position out. How much? It depends on the horn but every horn I own can be adjusted because I just vary how much distance off the bumper the first position needs to be. This way of tuning the horn would probably help you with your out of tune D on first. It may give you enough room to make it in tune.
2. Next is to try another more shallow mouthpiece. I've noticed that deeper mouthpieces affect higher partials to be flat. Not necessary too flat in the sense it makes a horn unplayable but in the way it needs to be adjusted differently with the slide. Maybe the size of mouthpiece you use fits another horn better, because I've noticed some horns are more picky with mouthpiece than others.
3. Finally you could let a tech shorten the tuningslide. I've done it on my Conn 88H I used when I was playing more symphony orchestra. I cut one cm on each side of the tuningslide which shortened the horn by a total of 2 cm. It was enough, but then here we tune A=442 or even higher sometimes. American instruments are constructed to be intune A=440, at least the old ones. I don't know if that has changed whith new instruments. If you are in Europe it is not uncommon to cut the tuningslide on an old Bach or Conn to be able to follow the strings when they play sharp and A might be 443 or even higher. For me the difference between A=440 and A=442 is about 1 cm on the slide. Since I do not move the tuningslide I have to vary were my first position is.
I was taught to play Bb in 1st position off the bumper. One of the reasons was to accommodate that flat 5th partial.
I also tend to play on the low side of the pitch center, so I have had to have the tuning slide cut down on every Bach trombone I've ever owned. On other instruments I tend to have the tuning slide nearly all the way in. It's not that complicated for a good tech to do.
) include some pictures too if possible so that I can follow exactly which part is being modified? Thank you so much in advance!